1. Field of the Invention
The present invention relates to a method and to an arrangement in accordance with the introductory portion of the appended claims. Especially, the invention relates to a method for launching and, respectively, taking aboard an independent floating object at the bow, side or stern of a ship or other transporting means in motion, or at any other arrangement which has a relative movement with respect to a surrounding medium. The present invention also relates to a device for use as a working platform at sea and especially for launching and, respectively, taking aboard a floating device at a ship or other transporting device, as well as to a steering device for a towed device and to a locking device for locking a floating device to a cradle arranged for said floating device.
2. Description of the Related Art
Since a long time prior art knows different davit arrangements for launching, in an emergency situation and otherwise, smaller boats and other floating devices. Known davit arrangements comprise beam means which usually can be turned or folded out over a ship's bulwark, and hoisting means for lowering and, in certain situations, also hoisting up floating devices like life boats, life saving rafts and the like. Arrangements are also known for launching such floating devices using special ramps without the use of davits, in which case one uses slides instead. In the latter arrangement very grave difficulties usually are included with any rehoisting of the floating device, and said devices are mostly intended for rescuing the ship's own crew.
Known davit arrangements have the drawback that launching and taking aboard a floating device in bad weather and at high waves is combined with very high risks. On the other hand, such circumstances often are at hand especially in those situations when a rescue vessel or the like floating device must be launched to perform a life saving operation. In known davit and the like arrangements a smaller floating device will be suspended directly in its hoisting means and in rough sea two mutually independent pairs of power will act upon the floating device. When said floating device is suspended in its hoisting means said means are fully stressed, while, on the other hand, when a wave hits the floating device said device often will be fully floating in slack hoisting means. In this position said hoisting means should be disconnected from the floating device, and, respectively, be connected to the floating device when it shall be hoisted on board again. It is clear that such an arrangement is especially unsuitable for hoisting and taking aboard a floating device in rough sea. In practice one will aim at turning the ship so that the work can be done in some kind of lee, but this is in no case possible in all situations, and thus one cannot in all conditions guarantee more than the launching. In rescue operations, on the other hand, the taking aboard of the rescued and the own personnel is of a decisive importance.
The international convention "Solas" (Safety of Life at Sea) will propose additional demands stating that a fast rescue boat must be on board all roll-on-roll-off passenger ships. Said fast rescue boat (FRB) must be quickly launchable from the mother ship on the move also during hard weather conditions and it must also be quickly hoistable back on board. This sets quite special demands on the equipment for launching and recovering on-board. One cannot see the possibility, using known hoisting means having a hoisting hook, to take aboard a rescue boat in the size of about 6 to 8 meters in a situation where the wave height is several meters. A boat of that size will vertically follow the wave, and an unhooking and hooking to e.g. a crane is under such circumstances difficult, dangerous and perhaps impossible.